Method of making mottled plastic sheet material



Jan. 20, 1953 LE ROY EABY 2,525,712

METHOD OF MAKING MOTTLED PLASTIC SHEET MATERIAL Filed NOV. 26, 1949 2 SHEETSSHEET 1 Jan. 20; 1953 LE ROY EABY 2,625,712

METHOD OF MAKING MOTTLED PLASTIC SHEET MATERIAL Filed Nov. 26 1949 2 SHEETS--SHEET 2 nnnnnnnnnrlnnunnnnnnnnnnnnn & gwuwvfm -2 LLeRoy E055] J A ZGL-H w L. I amw Patented Jan. 20, 1953 METHOD OF MAKING MOTTLED PLASTIC SHEET MATERIAL Le Roy Eaby, Lancaster, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Application November 26, 1949, Serial No. 129,546

' 9 Claims. (01. 18-483) This application is a continuation-in-part of my copending application, Serial No. 629,803, filed November 20, 1945, entitled Method of Making Mottled Plastic Sheet Material, now forfeited.

This invention relates to the manufacture of plastic sheet material having a ground of one or more colors and a veined or swirl-grain pattern of contrasting color or colors, generally similar in appearance to marble.

Plastic sheet material, such as asphalt tile, used generally for floor covering, has been made in the past by working the base mix and variegated color on a two-roll mill, stripping the material from the mill in the form of a sheet, cutting the sheet to the desired width, and then feeding the sheet in the cross-grain direction to a sheeting calender. This method requires that the sheets be handled individually by an operator between the mill and the calender. The separate pieces produced by this method, furthermore, have to be overlapped properly before the calendering in order to obtain uniform graining; and this operation requires a high degree of skill if heavy scrap losses resulting from improper graining at the points of overlapping are to be avoided.

I have invented a novel method of making sheet material, such as asphalt tile or linoleum, whereby the aforementioned objections to the previous practice are entirely overcome. In a preferred practice, I add premixed mottle color or colors to the base mix of the ground color or colors; and after dispersion of the former in the latter, I extrude the mix into mottlecolored strands or rods. These are then gathered or bunched and converted into a continuous strip by a single calendaring, producing a highly attractive swirl-grain pattern. The extruding operation serves to effect the principal spreading of the mottle color through the base mix. Passing the extruded mottle-colored rods through the sheeting calender creates the swirl grain by spreadinglaterally the mottle color already distributed longitudinally through the base mix as a result of the extrusion.

For a complete understanding of the invention, reference is made to the following detailed description and accompanying drawings illustrating a preferred practice diagrammatically. In the drawings:

Figure 1 is a plan view showing the arrangement of an extrusion press and a sheeting calender for processing a mix having mottle color distributed therethrough into a continuous 2 strip of plastic sheet material exhibiting a swirlgrain pattern;

Figure 2 is a side elevation thereof;

Figure 3 is a plan view showing a modification of my invention in which sheets of calendered material are formed into narrow strips having mottle color distributed therethrough; and

Figure 4 is a side elevation thereof.

In practicing my invention I prepare the base mix by charging the ingredients into a suitable mixer and working them therein for the required time. In making asphalt tile the usual proportions of binder, filler, and color may be employed, e. g., as disclosed in the Fredriksen Patent 1,939,045. If vinyl resin tile is to be made, the following composition will be found satisfactory:

Pounds Vinyl resin 100 Plasticizer (tricresyl phosphate) Stabilizer (white lead) 3 Filler and pigments 417 When the base composition has been sufficiently mixed, I add to it lumps of premixed mottle color or colors and continue the mixing for a limited time to insure distribution of the mottle color throughout the mix without causing it to be thoroughly blended therewith, as disclosed in the Fredriksen Patent aforementioned. That is to say, the mixing after the addition of the mottle color is terminated when the lumps of colorhave been more or less uniformly dispersed throughout the mix. The mix is then discharged from the mixer and charged into a piston-type extruding press, such as that indicated diagrammatically at ID.

The extruding press In is of known construction, including a cylinder having perforations II at one end and a piston (not shown) for pressing the contents of the cylinder through the perforations. By operation of the press, the base mix with the lumps of mottle color distributed therethrough is discharged in the form of rods or strands I2 onto any convenient receiving support such as a belt conveyor It. Any convenient means may be employed for cutting the strands or rods of the desired length.

The extrusion of the mix into rods or strands causes the mottle color to be distributed longitudinally, thereof. It also orients the fibers of the filler material, e. g., asbestos, in the direction of the length of the rods. If round rods are extruded, they preferably have a diameter of orless. The rods may, however, be in the form of fiat ribbons, say /2 wide and proaching more or less nearly the precise distribution illustrated.

The conveyor I3 delivers the rods or strands I2 into the nip of the upper or consolidating pair of rolls Id of a two-pass calender I5, the lower or sheeting pair of rolls of which are designated I6. The calender construction is more or less con ventional. The operation thereof converts the rods or strands delivered thereto by the conveyor I3 into a continuous strip I'I. As illustrated in the drawings, the conveyor I3 delivers extruded rods to the calender at a rate such that the'rods are bunched or grouped in a bank in the nip of the rolls. The desired condition in this respect can readily be obtained by correlating the speed of the calender and the rate of delivering the extruded rods thereto.

As shown, the rods lie on the rolls generally I parallel to the axes thereof, although here again the precise relation illustrated need not be achieved in practice. In fact, a considerable angularity of the rods relative to the roll axes and to each other has no detrimental effect. The rods may even be gathered or bunched in masses by hand and dropped onto the rolls in that form.

The upper rolls I4 of the calender squeeze the rods together, uniting or amalgamating them into a continuous strip, the width of which is roughly equal to the length of the rods, when disposed as shown in Figure 1, and having a thickness determined by the spacing between the rolls I4, preferably about The calendering of the rods causes the mottle color to be distributed laterally, i. e., at right angles to the length of the rods or in the direction of the length of the strip. The calendering also orients the filler fibers in a direction transverse to the length of the rods. The calendered strip, therefore, is characterized by proper distribution of the mottle color in both directions and orientation of the filler fibers longitudinally and transversely in the plane of the strip. As shown in the drawing, the sheet is formed wholly of mottle colored rods, disposed substantially parallel to the axes of the calender rolls, united into a variegated sheet with the graining thus formed extending substantially throughout the thickness of the sheet from the face to the back thereof.

The rolls I6 perform a finish calendering on the strip, reducing it to final gauge, say A, and elongating it correspondingly and causing a further lateral spreading of the mottle color. The finished strip may conveniently be delivered onto a belt conveyor I8 and carried to suitable shearing apparatus for trimming the side edges to the desired width and cutting the strip into blocks or pieces of the desired length.

In the modification shown in Figures 3 and 4 the mottle color is added to the base color in the mixers and the mixing is continued for a limited time to insure uniform distribution of the mottle color throughout the mix without causing it to be thoroughly blended therewith, as disclosed in the Fredriksen patent mentioned above; that is to say the mixing, after the addition of the mottle color, is terminated when the lumps of color have been more or less uniformly dispersed throughout the mix. The mix is then discharged from the mixer and charged to a two-roll mill. A blanket of the material is formed by the nip of a tworoll mill and follows one of the rolls. This blanket is allowed to pass through the nip of the rolls twice after which it is removed from the mill roll by means of a doctor blade and placed on a conveyor designated by the numeral IS in Figure 3. The blankets 20 are oriented on the conveyor so that the direction of graining of jaspe lines is perpendicular to the direction of travel of the conveyor I9. The blankets are preferably slightly overlapped in their edges so that the slitters will be working on the continuous stream of asphalt tile blankets. This overlap is shown by the numeral 2 I. As the blankets pass along the conveyor I9, they pass through a slitter 22 which cuts the blanket into narrow strips approximately 4" in width, the length of said strips being equal to the width of the blanket on the conveyor. The slitter 22 may be of any conventional type suitable for cutting asphalt tile blankets. It may be in the form of a rotary cutter or it may be a guillotine type slitter. Inasmuch as the slitter cuts the sheet into strips running across'the conveyor, and the blankets have been placed on the conveyor with the jaspe grain running perpendicular to the direction of travel of the conveyor, it will be clear that the cut strips 23 have the grain and fiber orientation running lengthwise thereof. The cut strips 23 continue along the conveyor I9 and fall into the bank of strips provided in the nip of the sheeting calender 24.

I The conveyor I9 delivers the strips 23 to a conventional two-pass calender 24 comprising a pair of consolidating, rolls 25 and a pair of finishing rolls 25. The calender construction is more or less conventional. The operation thereof converts thev strips delivered thereto into a continuous sheet. As illustrated in the drawings, the conveyor I9 delivers the strips 23 to the calender at a rate such that the strips are bunched or grouped in a bank in the nip of the rolls. The desired condition in this mass can readily be obtained by correlating the speed of the calender and the rate of delivery of the strips thereto.

As shown, the strips lie on therolls generally parallel to the. axes thereof although here; again the precise relation illustrated need not be achieved. in practice. In fact, a considerable angularity of the strips relativeto the roll axes and to each other has no detrimental effect. The strips may even be carried or bunched in masses by hand and dropped onto the rolls in that form. The upper rolls 25 of the calender squeeze the strips together uniting or amalgamating them into a continuous sheet, the width of which is roughly equal to the length of the strips when disposed as shown in Figure 3 and having, a thickness determined by the spacing between the rolls, preferably about The calendering of the strips causes the mottle color to be distributed laterally, that is, at right angles to the length of the strips or in the direction of the length of the sheet being calendered. The calendering also orients the filler fibers in a direction transverse to the length of the strips. The calendered sheet, therefore, is characterized by proper distribution of the mottle color in both directions and orientation of the filler fibers longitudinally and transversely in the plane of the strip. As shown in the drawing, the sheet is formed wholly of mottlecolored strips, disposed substantially parallel to the axes of the calender rolls, united into a variegated sheet with the graining thus formed extending substantially throughout the thickness of the sheet from the face to the back thereof.

The rolls 26 perform a finish calendering on the sheet, reducing it to its final gauge of approximately and elongating it considerably, causing a further lateral spreading of the mottle color. The finished sheet may conveniently be delivered onto a belt conveyor 21 and carried to suitable shearing apparatus for cutting the sheet into blocks or pieces of the desired dimension.

The blanket produced by the mill is approximately /1" thick, and the slitter is preferably set so as to out strips wide. With a setup of this type, strips A" x /4" by approximately 45 (the width of the blanket produced by the mill) will result. It will be clear from this that since the width and thickness of the strips is substantially the same some strips will pass through the calender with the surface exposed and other strips will pass through with the edge exposed. This aids in the production of variegated grain. While the strip dimensions given above are suitable for carrying out my invention, it will be understood that strips of other dimensions and general geometric configuration may also be satisfactorily used.

It will be apparent that my invention makes possible the production of a continuous strip of plastic sheet material having a swirl-grain pattern contrasting in color with the base mix or ground, without requiring any manual handling of the material during either the extrusion or calendering stage. I thus save the manual labor involved in the prior practice because of the necessity for turning the sheets or blankets between the initial milling and the final calendering to assure distribution of the color in both directions. A more important advantage is the fact that the finished product is free from joints, such as resulted from the lapping of successive pieces made according to the previous practice. This avoids the necessity for the skilled labor required to obtain uniform graining across the joints as well as the certain amount of scrap loss which is inevitable even when the highest skill is exercised in making the joints.

The product exhibits a highly attractive swirlgrain pattern with both an asphalt tile mix and a vinyl resin tile mix. It has been difficult to secure a marbleized effect in the latter by methods of manufacture used heretofore because of the high viscosity and toughness of such compositions.

Although I have illustrated and described but a preferred embodiment of my invention, it will be recognized that changes in the details of operation may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In a method of making variegated plastic sheet material, the steps including extruding a. mass of intermixed unblended ground and variegating color compositions into mottle-colored rods in which the variegating color composition is distributed longitudinally thereof, cutting said rods into lengths, feeding a mass of such rods in random arrangement into the nip of a sheeting calender in a quantity to maintain a bank of said rods in the nip with the length of the rods substantially parallel to the axes of the calender rolls, said rods being of a length not 6. greater than the width of the sheet to be formed, and irregularly blending the ground and variegating color compositions of the rods to distribute the variegating color composition laterally by compression of the mass of mottlecolored rods into the nip and through the calender rolls into a sheet formed substantially wholly from said rods disposed substantially parallel to the axes of the calender rolls, uniting the rods into an irregularly blended variegated sheet in which the graining is directed both longitudinally and transversely of the sheet'and extends substantially throughout the thickness of the sheet from the face to the back thereof.

2. A method in accordance with claim 1 in which the mottle-colored rods have a sectional area not substantially greater than .06 square inch.

3. A method in accordance with claim 1 in which the mottle-colored rods are generally cylindrical and have a diameter not substantially greater than A".

4. A method in accordance with claim 1 including as an additional step the passage of the irregularly blended variegated sheet between a pair of sheeting calender rolls for reducing the thickness of the sheet and further blending the color compositions.

5. In the method of making variegated plastic sheet material, the steps including feeding a mass of mottle-colored rods comprising intermixed ground and variegating color compositions, said variegating color compositions being distributed longitudinally of said rods, in random arrangement into the nip of a sheeting calender in a quantity to maintain a bank of said rods in the nip with the length of the rods substantially parallel to the axes of the calender rolls, said rods being of a length no greater than the width of the sheet material to be formed, and irregularly blending the ground and variegating color compositions of the rods to distribute the variegating color composition laterally by compression of the mass of mottle-colored rods into the nip and through the calender rolls into a sheet formed substantially wholly of said rods disposed substantially parallel to the axes of the calender rolls, and uniting the rods into an irregularly blended variegated sheet in which the graining is directed both longitudinally and transversely of the sheet and extends substantially throughout the thickness of the sheet from the face to the back thereof.

6. In the method of making variegated plastic sheet material, the steps including forming a sheet of mottle-colored intermixed unblended ground and variegating color compositions in which the variegating color composition is distributed longitudinally thereof, severing said sheet into relatively narrow rods, feeding a mass of such rods in random arrangement into the nip of a sheeting calender in a quantity to maintain a bank of said rods in the nip with the severed edges of some of the rods exposed and the calendered edges of other rods exposed, said rods being of a length not greater than the width of the sheet to be formed, and irregularly blending the ground and variegating color compositions of the rods to distribute the variegating color composition laterally by compression of the mass of mottle-colored rods into the nip and through the calender rolls into a sheet formed substantially wholly from said rods disposed sub stantially parallel to the axes of the calender 7 rollamiiting the rods into an irregularly blend: ed variegated sheet in which the grain is directed both longitudinally and transversely of thesheet and extends substantially throughout the thickness of the sheet from the face to the back thereof.

'7. A method in accordance with claim 6 in which the mottle-colored rods have a sectional area not substantially greater than .0625 square inch.

8. A method in accordance with claim 6 in which the mottle-colored rods are generally rectangular in cross section and are approximately V in width and A in thickness.

9. A method in accordance with claim 6 including as an additional step the passage of the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,763,314 McConoughey June 10 1930 2,260453 Hartman Oct. 28, 1941 2,369,866 Spencer Feb. 20, 1945 2,370,536

Hartman Feb. 2'7, 1945 

